Linkage system

ABSTRACT

A linkage system (1) for connecting a first element (2) and a second element (3) includes a linkage arm (4) respectively connected at a first end and a second end (5, 6) respectively to the first and second elements. Arm (4) includes at end (5) two spaced apart engagement formations, pin (7) and pin (8). These pins slidably inter-engage on the first element a guide slot (9) and a control slot (10) respectively. Relative movement between pins (7, 8) and the guide and control slot (9, 10) respectively provides predetermined non-arcuate relative movement between elements (2, 3).

TECHNICAL FIELD

The present invention relates to a linkage system.

The invention has been developed primarily for use with adjustablefurniture and in particular height adjustable desks and will bedescribed hereinafter with reference to that application. However, itwill be appreciated that the invention is not limited to that particularfield of use.

BACKGROUND ART

Hitherto, height adjustment mechanisms for desks have included a singlelinkage arm which extends between and is rotatably connected to both afixed support and a movable support. Although movement of the movablesupport between a raised and lowered configuration is accommodated, thatmovement is limited to rotation through an arc having an axis passingthrough the connection point between the arm and the fixed support.Additionally, a single arm is often subject to large twisting momentswhich results in wear and requires that the arm be produced from heavygauge materials.

Alternative prior art systems utilise a pantographic mechanism which,while providing greater effective strength, is generally of increasedcost and complexity. Moreover, the path followed by the movable supportis still substantially arcuate.

Accordingly, hereinafter the term arcuate movement will be taken toinclude movement that results from the prior art single linkage andpantographic linkage mechanisms.

An additional problem of the prior art resides in the fact thateffective strength of the pantographic mechanism is dependant upon thedistance between the two arms. Although an increase in this distancewill provide an increase in the strength, it also results in a muchlarger, and at times cumbersome, mechanism. This is particularlydisadvantageous for adjustable desks were a larger mechanism causes areduction in leg room beneath the movable surface.

DISCLOSURE OF THE INVENTION

It is an object of the present invention, at least in a preferredembodiment, to overcome or substantially ameliorate at least some ofthese deficiencies of the prior art. According to the invention there isprovided a linkage system for connecting a first element having a guideformation and a control formation and a second element, the systemincluding a linkage arm respectively connected at a first end and asecond end to the first and second elements, the arm including at thefirst end two spaced apart engagement formations for slidablyinter-engaging the guide formation and the control formationrespectively, whereby relative movement between the first and secondformations and the guide and control formations respectively providesfor predetermined non-arcuate relative movement between the first andsecond elements.

Preferably, the engagement formations are hinge pins and the guide andcontrol formations are both slots in the first element for respectivelyreceiving the pins. More preferably, one of the slots includes lockingformations for selectively engaging a respective pin for maintaining thefirst and second elements in one of a number of relative dispositions.Even more preferably, the first element comprises a fixed supportbracket for attachment to a desk surface and the second elementcomprises a keyboard support bracket for attachment to a keyboardsupport, whereby, in use, said keyboard support is movable between araised and lowered configuration with respect to the desk. However, inalternative embodiments the first and second elements comprise thekeyboard support bracket and the fixed. support bracket respectively.

Preferably also, the linkage system includes a support arm extendingbetween the first and second elements. More preferably, the support armis rotatably connected at respective ends to the first and secondelements. Even more preferably, the support arm is hingedly and slidablyconnected at one end to one of the first and second elements.

In a preferred form, the connections of the linkage and guide arms to atleast one of the first and second elements are spaced apart. Morepreferably, the spacing between the connections of the linkage and guidearms to the first element is greater than the spacing between theconnections of those arms to the second element.

BRIEF DESCRIPTION OF THE DRAWINGS

A number of preferred embodiments of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 is a schematic side view of a linkage system in accordance withthe invention;

FIG. 2 is a fragmented view of the linkage system of FIG. 1 illustratingalternative locking means;

FIG. 3 is alternative embodiment of a linkage system according to theinvention;

FIG. 4 is a further alternative embodiment of the invention;

FIG. 5 is a perspective view of another alternative linkage system inaccordance with the invention.

FIG. 6 is a schematic side view of the linkage system of FIG. 5;

FIG. 7 is a schematic side view of the linkage system of FIG. 5including alternative locking means;

FIG. 8 is a schematic side view of the linkage system of FIG. 7 in use;

FIG. 9 is a schematic side view of an alternative linkage systemaccording to the invention;

FIG. 10 is an exploded side view of a further alternative embodiment ofa linkage system according to the invention; and

FIG. 11 is a side view of the linkage system of FIG. 10 when assembled.

MODES FOR CARRYING OUT THE INVENTION

Referring to the drawings, and particularly to FIGS. 1 and 2, a linkagesystem 1 for connecting a first element 2 and a second element 3includes a linkage arm 4 respectively connected at a first and a secondend 5 and 6 respectively to the first and second elements. Arm 4includes at end 5 two spaced apart engagement formations, pin 7 and pin8. These pins slidably inter-engage on the first element a guide slot 9and a control slot 10 respectively. Relative movement between pins 7 and8 and the guide and control slot 9 and 10 respectively providespredetermined non-arcuate relative movement between elements 2 and 3.

In this particular embodiment element 2 is configured for abutment onthe undersurface of a desk while end 6 of arm 4 is attached to akeyboard support (not shown). The keyboard support is moved along apredetermined non-arcuate path designated by broken line 11 as end 3moves between its extremes of travel. Path 11 is defined by theinteraction of the pins in the control and guide slots. As will beappreciated by those skilled in the art the slots can be varied in shapeto suite a particular application.

In FIG. 1 the locking mechanism is formed by an array of teeth 12 alongthe top edge of slot 10 and a complimentary smaller array of teeth 13along adjacent top edge of pin 8. These teeth are shown in thedisengaged configuration to allow pins 7 and 8 to translate along slots9 and 10.

In use, end 6 of arm 4 will be biased downwardly due to the presence ofthe keyboard support and/or a keyboard. Accordingly, the teeth 12 and 13will be biased into a locked configuration. To effect height adjustmentthe keyboard support is lifted or tilted upward to overcome thegravitational bias and subsequently by applying a force to arm 4 whichcauses the translation of the pins 7 and 8 in the slots 9 and 10respectively. Upon reaching a desired position the keyboard support canbe released and the gravitational bias will again move teeth 12 and 13into locking inter-engagement.

FIG. 2 illustrates an alternative embodiment of the invention wherecorresponding features are designated with corresponding referencenumerals. This linkage system is substantially the same as thatdisclosed in FIG. 1 with the exception that the teeth 12 and 13 aretriangular in nature to facilitate movement into a locked configuration.Other embodiments include a ratchet style of locking arrangement tofacilitate upward movement of the keyboard support while requiring theteeth to be fully moved out of a locked configuration before downwardmovement can be achieved.

Turning now to FIG. 3 an alternative embodiment of the invention isshown. Linkage system 15 includes a fixed support bracket 16 formounting to a desk or the like and a keyboard support bracket 17 whichis mounted to bracket 16 by way of linkage arms 18 and 19.

Bracket 16 includes three parallel slots 20, 21 and 22 for slidablyreceiving pins 23, 24 and 25 respectively. These pins are joined by wayof a triangular frame 26 to ensure simultaneous progression of the pinsalong the slots. Bracket 16 also includes a guide slot 27 which slidablyreceives a pin 28 which is intermediately located along arm 19.

This slot configuration enables keyboard support bracket 17 to move in asubstantially vertical direction upon horizontal translation of frame26. Again, this translation is effected by the interaction between theguide and control slots and is substantially a linear translation.

If required, the movement of the keyboard support bracket between theraised and lowered configurations can be assisted by way of biasingmeans or, for example, a pneumatic cylinder extending between frame 26and bracket 16. In addition, locking means can be included toselectively retain the frame at one of a number of dispositions tosubsequently maintain bracket 17 at a particular height.

A further alternative embodiment is shown in FIG. 4. More particularly,a fixed support bracket 30 includes two identical spaced apart guideslots 31 which receive respective first ends 32 of two hinged linkagearms 33. These arms are slidably and rotatably engaged to bracket 30 bya pin 34 and at their second ends 35 engage a movable support bracket(not shown). Arms 33 are sloted to effect the slidable and rotatableconnection to pin 34.

Arms 33 move in unison between the configuration shown and theconfiguration designated by broken lines 36. When moving between theseconfigurations ends 35 trace a path designated by broken lines 37 due tothe interaction between arms 33, guide slots 31 and pins 34. In thisparticular embodiment the path traced by line 37 includes a combinationof arcuate and linear paths. Alternative combinations are possible byvarying the shape of slots 31.

Referring now to FIG. 5 and FIG. 6, there is illustrated a furtherembodiment of the invention. The linkage mechanism 40 illustratedincludes a pair of opposed support brackets 41 and 42 which are adaptedto be fixed to the underside of a desk surface by way of screws, rivetsor the like. Brackets 41 and 42 are joined to respective adjacentkeyboard support bracket 43 and 44 by way of linkage arms 45 and 46, and47 and 48 respectively. Arms 45 and 47 are joined by a rectangularsection cross member 49 to ensure simultaneous movement between thesearms.

Arms 45 and 47 are rotatably and slidably connected to respectivebrackets 41 and 42 by pins 50 and slots 51 while being only rotatablyconnected to brackets 43 and 44 by pins 52. Arms 46 and 48, however, arerotatably connected to both brackets by way of pins 53 and 54. Inaddition, arms 45 and 47 include pins 55 which are captively retainedwithin slots 56 in brackets 41 and 42.

As best shown in FIG. 5, linkage system 40 includes locking means 57 forselectively maintaining the brackets 43 and 44 at a relative height withrespect to brackets 41 and 42. Locking means 57 comprises a biased plate58 which is operable by handle 59 for moving slots 60 into and out ofengagement with one or more locking protrusions (not shown) located onarm 48. Alternative locking arrangements are known.

Referring now in particular to FIG. 6, bracket 44 is able to progressbetween a raised and lowered configuration, as shown. During thisprogression, pins 50 and 55 respectively traverse slots 51 and 56 toprovide a non-arcuate path for bracket 44.

The progression of bracket 44 involves both vertical and horizontalmovement. The linkage system 40 continues to provide the same degree ofvertical movement that was obtained from prior art pantographicmechanisms, while reducing the amount of horizontal movement. Ifrequired, and as illustrated by way of example in FIG. 3, slots 51 and56 can be appropriately shaped to eliminate horizontal movement.

The vertical distance between pins 52 and 54 is approximately 60 mm,while the vertical separation between pins 50 and 53 is at least 70 mm.This non-pantographic arrangement provides an increase in strength of atleast 30% over a standard pantographic mechanism having a spacing of 60mm between the arms. Most advantageously, this increase in strength isachieved without increasing the depth of bracket 44 and therebymaintaining the original leg room provided under that bracket.

Referring to FIG. 7 and FIG. 8, where corresponding features are denotedwith corresponding reference numerals, linkage system 40 includesalternative locking means. More particularly, slot 56 includes aplurality of alternating small and large semi-circular lockingformations 61 for selectively captively retaining pin 55. Pin 55 ismoved out of engagement with the formations 61 by applying an upwardforce in the direction of arrow 62 to overcome the gravitational biasprovided by bracket 44. Thereafter, pin 55 can be progressed along slot56, while pin 50 will simultaneously progress along slot 51. When thedesired position has been achieved the force applied the bracket 44 isreleased and pin 55 will move into engagement with an adjacent formation61.

The different sized interspaced locking formations 61 provide a degreeof tilt adjustment for bracket 44. This is best shown in FIG. 8, wherebracket 42 is slidably mounted within a track 62 which extends along thebottom surface 63 of a desk 64. Additionally, bracket 44 is secured to akeyboard support 65 which supports a keyboard 66. In the configurationshown, bracket 42 and 44 are nested beneath desk 64, and in addition,pin 55 is engaged with one of the smaller formations 61 to incline end67 of keyboard support 65 toward surface 63. This provides a convenientmode for storage for keyboard 66 which can be retrieved, as required, byadvancing bracket 42 along track 62 and subsequently adjusting theheight of bracket 44, as described above.

The embodiment of the invention illustrated in FIG. 9 is similar to thatof FIGS. 7 and 8 and as such corresponding features will be denoted withcorresponding reference numerals. However, slot 56 is a compound slotcomprised of a series locking positions 68. Once pin 55 is in one ofpositions 68 it will remain so disposed until an upward force isprovided on bracket 44 to overcome the locking bias. Advantage is againused of the interaction between slots 51 and 56 and pins 50 and 55respectively to provide a simple and effective locking mechanism and anon-arcuate path between the raised and lowered configurationillustrated.

A further embodiment of the invention is shown in FIGS. 10 and 11 whichare schematic side views of a linkage system 70. The linkage systemincludes a first bracket 71 having two spaced apart apertures 72 and 73for receiving bolts, rivots or pins 74 and 75 for rotatably mountingarms 76 and 77 to the bracket. The arms include respective apertures 78and 79 for receiving pins 74 and 75.

The distal ends of arms 76 and 77 are mounted to a movable bracket 80for allowing movement of that bracket between a raised and loweredconfiguration, as best shown in FIG. 11. More particularly, arm 76includes at its distal end an aperture 81 and a slot 82 spaced from thataperture. Arm 77, however, includes at its distal end a single aperture83.

In use, a pin 84 passes through aperture 85 in bracket 80, aperture 83in arm 77 and slot 82 in arm 76. A further pin 86 passes through slot 87in bracket 80 and aperture 81 in arm 76. During progression of bracket80 between the raised and lowered configurations shown in FIG. 8 pins 84and 86 progress along slots 82 and 87 respectively.

The substantially linear, non-arcuate progression of bracket 80 isparticularly advantageous for height adjustable desk linkage systems.

A locking mechanism can be incorporated with linkage system 70 toselectively maintain bracket 80 at a predetermined disposition withrespect to bracket 71. For example, one of slots 82 or 87 can includelocking formations for receiving respective pins 84 and 82. Alternativearrangements would be apparent to those skilled in the art.

It will be appreciated that many different known locking mechanismssuitable for use with one or more of the embodiments described above.

Although the invention has been described with reference to specificexamples, it will be appreciated by those skilled in the art that theinvention may be embodied in many other forms. For example, the controland guide formations can provide a degree of flexibility for a linkagearm suitable for robotics and related applications.

I claim:
 1. A linkage system comprising:a first element defining a guideslot and a control slot; a second element; a linkage arm respectivelyconnected at a first end and a second end to the first and secondelements, the linkage arm including at the first end a first hinge pinfor slidably inter-engaging the guide slot and spaced apart from saidfirst hinge pin, a second hinge pin for slidably inter-engaging thecontrol slot, whereby relative movement between the hinge pins and theguide slot and the control slot respectively provides for predeterminednon-arcuate relative movement between the first and second elements; andlocking formations for selectively engaging one of the hinge pins formaintaining the first and second elements in one of a number of relativepositions, said locking formations extending into at least one of thecontrol slot and the guide slot.
 2. A linkage system according to claim1 wherein one of the first and second elements comprises a fixed supportbracket for attachment to a desk surface and the other one of the firstand second elements comprises a keyboard support bracket for attachmentto a keyboard support, whereby, in use, the keyboard support is movablebetween a raised configuration and a lowered configuration with respectto the desk surface.
 3. A linkage system according to claim 1 furthercomprising a second linkage arm extending between the first and secondelements.
 4. A linkage system according to claim 3 wherein the secondlinkage arm is rotatably connected at respective ends to the first andsecond elements.
 5. A linkage system according to claim 3 wherein thesecond linkage arm is hingedly and slidably connected at an end to oneof the first and second elements.
 6. A linkage system according to claim5 wherein the linkage arm and the second linkage arm are spaced apart atone of the first and second elements.
 7. A linkage system according toclaim 5 wherein the linkage arm and the second linkage arm are spacedapart at the first element and at the second element, the spacingbetween the linkage arm and the second linkage arm being greater at thefirst element than at the second element.
 8. A linkage system accordingto claim 1 wherein said hinge pins are fixedly spaced apart.
 9. Akeyboard support apparatus comprising:a first element having a guideformation and a control formation; a second element; a linkage armrespectively connected at a first end and a second end to the first andsecond elements, the linkage arm including at the first end a firstengagement formation for slidably interengaging the guide formation andspaced apart from said first engagement formation, a second engagementformation for slidably engaging the control formation, whereby relativemovement between the engagement formations and the guide formation andthe control formation respectively provides for predeterminednon-arcuate relative movement between the first and second elements; andwherein one of the first and second elements comprises a support bracketfor attachment to a desk surface, and the other one of the first andsecond elements comprises a keyboard support bracket for attachment to akeyboard support, whereby, in use, the keyboard support is movablebetween a raised configuration and a lowered configuration with respectto the desk surface.
 10. A keyboard support apparatus according to claim9 wherein the engagement formations are comprised of hinge pins;andwherein the guide formation is comprised of a guide slot formed inthe first element, and the control formation is comprised of a controlslot formed in the first element, the guide slot and the control slotbeing adapted to receive the hinge pins.
 11. A keyboard supportapparatus according to claim 10 further comprising locking formationsfor selectively engaging one of the hinge pins so as to maintain thefixed support bracket and the keyboard support bracket in one of anumber of relative dispositions, said locking formations extending intoat least one of the guide slot and the control slot.
 12. A keyboardsupport apparatus according to claim 9 further comprising a secondlinkage arm extending between the fixed support bracket and the keyboardsupport bracket.
 13. A keyboard support apparatus according to claim 12wherein the second linkage arm is rotatably connected at respective endsto the fixed support bracket and the keyboard support bracket.
 14. Akeyboard support apparatus according to claim 12 wherein the secondlinkage arm is hingedly and slidably connected at an end to one of thefixed support bracket and the keyboard support bracket.
 15. A keyboardsupport apparatus according to claim 14 wherein the linkage arm and thesecond linkage arm are spaced apart at one of the fixed support bracketand the keyboard support bracket.
 16. A keyboard support apparatusaccording to claim 15 wherein the linkage arm and the second linkage armare spaced apart at the fixed support bracket and at the keyboardsupport bracket, the spacing between the linkage arm and the secondlinkage arm being greater at the fixed support bracket than at thekeyboard support bracket.
 17. A keyboard support bracket according toclaim 9 wherein said engagement formations are fixedly spaced apart.